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Results for “computational design”

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At least 127 records · Page 7Linked to original sources
PubMed2006

Genetic algorithms as a tool for helix design--computational and experimental studies on prion protein helix 1.

Evolutionary computing is a general optimization mechanism successfully implemented for a variety of numeric problems in a variety of fields, including structural biology. We here present an evolutionary approach to optimize helix stability in peptides and proteins employing the AGADIR energy function for helix stability as scoring function. With the ability to apply masks determining positions, which are to remain constant or fixed to a certain class of amino acids, our algorithm is capable of developing stable helical scaffolds containing a wide variety of structural and functional amino acid patterns. The algorithm showed good convergence behaviour in all tested cases and can be parameterized in a wide variety of ways. We have applied our algorithm for the optimization of the stability of prion protein helix 1, a structural element of the prion protein which is thought to play a crucial role in the conformational transition from the cellular to the pathogenic form of the prion protein, and which therefore poses an interesting target for pharmacological as well as genetic engineering approaches to counter the as of yet uncurable prion diseases. NMR spectroscopic investigations of selected stabilizing and destabilizing mutations found by our algorithm could demonstrate its ability to create stabilized variants of secondary structure elements.

Algorithms↗
PubMed2006

Computational design of a single amino acid sequence that can switch between two distinct protein folds.

The functions of many proteins are mediated by specific conformational changes, and therefore the ability to design primary sequences capable of secondary and tertiary changes is an important step toward the creation of novel functional proteins. To this end, we have developed an algorithm that can optimize a single amino acid sequence for multiple target structures. The algorithm consists of an outer loop, in which sequence space is sampled by a Monte Carlo search with simulated annealing, and an inner loop, in which the effect of a given mutation is evaluated on the various target structures by using the rotamer packing routine and composite energy function of the protein design software, RosettaDesign. We have experimentally tested the method by designing a peptide, Sw2, which can be switched from a 2Cys-2His zinc finger-like fold to a trimeric coiled-coil fold, depending upon the pH or the presence of transition metals. Physical characterization of Sw2 confirms that it is able to reversibly adopt each intended target fold.

Algorithms↗
PubMed2003

Computational design of solar reflection and far-infrared transmission films for a variable emittance device.

A smart radiation device (SRD) that is a variable emittance radiator has been studied as a method of thermal control for spacecraft. The SRD consists of manganese oxide with a perovskite-type structure, and the total hemispherical emittance of the SRD changes considerably depending on temperature. Here we propose an optimal method of designing multilayer films for the SRD by using agenetic algorithm. The multilayer films reflect solar radiation and transmit far-infrared radiation to maintain variation of the infrared optical properties of the SRD.

Journal Article↗
PubMed2005

Computational design for guided-mode grating resonances.

We are concerned with optimal design of guided-mode grating resonant structures (GMGRs). A typical structure is the integration of a zeroth-order grating and a planar waveguide. Our approach has two main steps. The first is to find the resonant wavelength. For any fixed grating structure the resonant wavelength is found by solving a nonlinear eigenvalue problem. The second step is to develop a Newton-type local optimization method. A crucial step is to determine an appropriate initial guess of the design parameters. Numerical design examples for both TE and TM polarization are presented. The design algorithm is expected to provide systematic guidance in engineering design of GMGRs.

Journal Article↗
PubMedDate not supplied

Designing computer support for daily hospital staffing decisions.

This paper relates issues encountered in extending a centralized computer-based nurse scheduling system to support daily staffing decisions in a hospital environment. When calculating the daily staffing needs on each nursing unit, the conceptually simple interactive staffing system incurred considerable costs in categorizing patients according to level of care required. Two years of historical data collected daily in a 568 bed St. Louis hospital were used to test the sensitivity of relative staffing requirements to daily fluctuations in patient-care distributions. A periodic sampling plan appears adequate for updating distributions which can then be applied to current census in estimating daily staffing needs. Recommendations for implementing such a system are offered.

Computers↗
PubMed1992

Designing computer assisted instruction programs for diabetic patients: how can we make them really useful?

Despite the increasing potential of computers for educational use, experience shows that few Computer Assisted Instruction (CAI) programs for patient education have been accepted into routine use by health care providers. A CAI program on hypoglycemia for insulin dependent diabetics, which was developed by the authors and has been widely used in Europe for over 6 years, is described and is used to illustrate some specific difficulties and possible solutions when using computers for patient education. We hope to show that patients suffering from a chronic disease, such as diabetes, require specific skills which are very different in nature from the theoretic knowledge they usually receive from different sources, including health care providers. In order to be really useful, a CAI program for patients must help them to cope with their disease and take into account patients' concerns, fears, and misconceptions as far as possible. Far beyond a detailed knowledge of the domain, a deep experience in patient education is mandatory to understand patients' needs.

Artificial Intelligence↗
PubMed1990

Computer-aided design and computer-aided manufacturing (CAD/CAM) in prosthetics.

Computer-aided design and computer-aided manufacturing (CAD/CAM) systems for the design and manufacture of limb prostheses have recently become commercially available. However, rigorous evaluations of these systems have not been performed to determine whether they produce sockets that fit as well as or better than sockets made using conventional design methods. A controlled evaluation protocol, in which computer-designed sockets are compared with conventionally designed sockets, has been developed and pilot tested at the authors' facility. A full trial of one of the commercially available systems for transtibial sockets is currently in progress. In preliminary findings, the CAD/CAM socket was preferred by one-half of the first 20 subjects. During the course of this trial, it was noted that the CAD/CAM technique seems to be better suited to some prosthetists than others.

Adult↗
PubMed1990

Computer-Aided Design and Computer-Aided Manufacture (CAD-CAM) applications in cosmetic below-elbow prostheses.

Computer-Aided Design and Computer-Aided Manufacture (CAD/CAM) techniques, though often technologically associated with engineering and applied sciences, has opened new horizons in the medical field. In CAD, a product is first geometrically modelled in three dimensions in a computer and it can be viewed and examined from any direction. This model can then be used for many downstream applications such as manufacturing and analysis. In CAM, numerically controlled machining processes are used for cutting out a prosthetic device of the hand for prosthesis. The paper aims at establishing the basis of using CAD/CAM techniques in prostheses in particular, a review of our present work done in the area of below-elbow prostheses using CAD/CAM. A laser scanning device has been used to capture the geometry of human hands. The algorithm used in processing the images is discussed. The processed 3D data file is then interfaced with a CAD modeller where reconstruction, mirroring, scaling, etc., can be performed. The resultant CAD model is then passed on to CAM, which concentrates purely on producing a "positive core" mould for moulding the prosthetic device.

Algorithms↗
PubMed1999

A new technique for generating a computer-aided design and computer-integrated machining crown: case report.

A new technique for producing a Computer-Aided Design and Computer-Integrated Machining Ceramic Reconstruction crown is presented. After completion of the tooth preparation, an "optical" impression of the tooth was made with a charged couple device camera, and the electronic image was transferred to a computer screen. The "proposed" crown was electronically designed on the screen by the operator, and a proper prefabricated ceramic block was selected and used as milling material. A miniature milling machine then fabricated the crown from the ceramic block. The marginal adaptation and the contour of the crown were verified, and an external shading technique was utilized to improve the esthetics. The prepared tooth and crown were acid-etched, and the crown was cemented with a dual-curing composite luting agent. Once bonded in place, the occlusion was adjusted and the crown polished and finished. The advantage of this technique is that it eliminates the traditional laboratory casting procedure and corresponding laboratory fee while utilizing materials with superior physical properties for maximum strength and esthetics.

Adult↗
PubMed1994

Advances in computer-aided design and computer-aided manufacture technology.

Although the development of computer-aided design (CAD) and computer-aided manufacture (CAM) technology and the benefits of increased productivity became obvious in the automobile and aerospace industries in the 1970s, investigations of this technology's application in the field of dentistry did not begin until the 1980s. Only now are we beginning to see the fruits of this work with the commercial availability of some systems; the potential for this technology seems boundless. This article reviews the recent literature with emphasis on the period from June 1992 to May 1993. This review should familiarize the reader with some of the latest developments in this technology, including a brief description of some systems currently available and the clinical and economical rationale for their acceptance into the dental mainstream. This article concentrates on a particular system, the Cerec (Siemens/Pelton and Crane, Charlotte, NC) system, for three reasons: first, this system has been available since 1985 and, as a result, has a track record of almost 7 years of data. Most of the data have just recently been released and consequently, much of this year's literature on CAD-CAM is monopolized by studies using this system. Second, this system was developed as a mobile, affordable, direct chairside CAD-CAM restorative method. As such, it is of special interest to the dentist who will offer this new technology directly to the patient, providing a one-visit restoration. Third, the author is currently engaged in research using this particular system and has a working knowledge of this system's capabilities.

Ceramics↗
PubMedDate not supplied

Advances in computer-aided design and computer-aided manufacture technology.

Although the development of computer-aided design (CAD) and computer-aided manufacture (CAM) technology and the benefits of increased productivity became obvious in the automobile and aerospace industries in the 1970s, investigations of this technology's application in the field of dentistry did not begin until the 1980s. Only now are we beginning to see the fruits of this work with the commercial availability of some systems; the potential for this technology seems boundless. This article reviews the recent literature with emphasis on the period from June 1992 to May 1993. This review should familiarize the reader with some of the latest developments in this technology, including a brief description of some systems currently available and the clinical and economical rationale for their acceptance into the dental mainstream. This article concentrates on a particular system, the Cerec (Siemens/Pelton and Crane, Charlotte, NC) system, for three reasons: First, this system has been available since 1985 and, as a result, has a track record of almost 7 years of data. Most of the data have just recently been released and consequently, much of this year's literature on CAD-CAM is monopolized by studies using this system. Second, this system was developed as a mobile, affordable, direct chairside CAD-CAM restorative method. As such, it is of special interest to the patient, providing a one-visit restoration. Third, the author is currently engaged in research using this particular system and has a working knowledge of this system's capabilities.

Computer-Aided Design↗
PubMed2005

Specificity versus stability in computational protein design.

Protein-protein interactions can be designed computationally by using positive strategies that maximize the stability of the desired structure and/or by negative strategies that seek to destabilize competing states. Here, we compare the efficacy of these methods in reengineering a protein homodimer into a heterodimer. The stability-design protein (positive design only) was experimentally more stable than the specificity-design heterodimer (positive and negative design). By contrast, only the specificity-design protein assembled as a homogenous heterodimer in solution, whereas the stability-design protein formed a mixture of homodimer and heterodimer species. The experimental stabilities of the engineered proteins correlated roughly with their calculated stabilities, and the crystal structure of the specificity-design heterodimer showed most of the predicted side-chain packing interactions and a main-chain conformation indistinguishable from the wild-type structure. These results indicate that the design simulations capture important features of both stability and structure and demonstrate that negative design can be critical for attaining specificity when competing states are close in structure space.

Bacterial Proteins↗
PubMed1990

Principles and applications of Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) technology in orthopaedics.

The principles involved in Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) technology is presented in this article. It also highlights the current advances and capability of this technology. Application of the CAD/CAM technology in orthopaedics is relatively new. Three broad areas of applications can be defined: (1) three-dimensional reconstructions of skeletal structure based on any of the imaging technique, i.e. CT scan, MRI or X-ray, to analyse, simulate, design and evaluate orthopaedic procedures without having to actually perform the surgery; (2) the production of plastic or wax models for surgeons to have global impressions and understanding of complex cases of bone and joint disorders and the possibility of using the physical models as templates to sculpt allograft pre-operatively; and (3) to design and manufacture geometrically optimal standard and customised implants. CAD/CAM technology is also rapidly developing in the field of prosthetics, orthotics and orthopaedics footwear. The advantages offered include shorter delivery time, more consistent design, quantifiable rectification and "modern" or remote manufacturing. Apart from these applied usage, the CAD/CAM technology is also an effective tool for education and training. The application of CAD/CAM technology in orthopaedics and its related fields has been shown to have tremendous potential, but may appear to be too esoteric, complex and costly at the present moment. However, with improved generality, simplicity and cost-effectiveness of the system, it will become more practical.

Computer Simulation↗